1. Technical Field
The present disclosure relates to an organic light-emitting display panel and a display device comprising the same. More specifically, the present disclosure relates to an organic light-emitting display panel capable of improving color purity and color gamut by reducing optical interference between adjacent pixel areas, and a display device comprising the same.
2. Description of the Related Art
As the information-oriented society evolves, various demands for display devices are ever increasing. In accordance with this, display devices are being developed and released, with a variety of display panels such as a liquid-crystal display panel, a plasma display panel, an organic light-emitting display panel, etc.
Among these, an organic light-emitting display (OLED) device employing an organic light-emitting display panel is a self-luminance display device. Accordingly, an OLED device, unlike a liquid-crystal display device, does not require a separate light source and thus it can be made lighter and thinner. Further, an organic light-emitting display device can be driven with low voltage and have excellent color reproduction, short response time, wide viewing angle and good contrast ratio. Accordingly, an organic light-emitting display device is widely used recently.
OLED devices may be divided into a RGB display device in which an organic emission layer emitting a different color is disposed in each of pixel areas, and a white emission/color filter (W+CF) display device in which an organic emission layer emitting white light and a color filter defining a different color are disposed in each of pixel areas.
For a RGB organic light-emitting display device, sub-pixel areas corresponding to R, G and B, respectively, are defined on a substrate by using a fine metal mask. As display devices become larger and have higher resolution, such fabricating process using a fine metal mask becomes more difficult. For this reason, white emission/color filter (W+CF) OLED devices are more preferred recently.
White emission/color filter (W+CF) OLED devices may be divided into three-color OLED device in which a red pixel area, a blue pixel area and a green pixel area are defined on a substrate, and four-color OLED device in which a white pixel area, as well as a red pixel area, a blue pixel area and a green pixel area, is defined on a substrate.
FIG. 1 is a cross-sectional view of an existing three-color OLED device. FIG. 2 is a cross-sectional view of an existing four-color OLED device.
The OLED devices shown in FIG. 1 and FIG. 2 are bottom emission display devices in which light is emitted from an organic emission layer toward a layer that includes a driving thin-film transistor.
Referring to FIG. 1 and FIG. 2, a driving thin-film transistor DTr including a gate electrode 110, an insulation layer 120, a semiconductor layer 130, an etch stopper 140, a source electrode 150a and a drain electrode 150b is disposed on a substrate 100.
Then, a passivation layer 160 is disposed on the driving thin-film transistor DTr. A planarization layer 165 having a hole 165a formed therein is disposed on the passivation layer 160, and a first electrode 170 is formed on the passivation layer 165 and is electrically connected to a drain electrode 150b of the driving thin-film transistor DTr via the hole 165a. 
Then, a bank layer 190 is disposed along the edge of the first electrode 170 to cover a part of it. The organic emission layer 175 is disposed on a part of the first electrode 170 exposed between openings of the bank layer 190, and a second electrode 180 is disposed on the organic emission layer 175. The first electrode 170, the organic emission layer 175 and the second electrode 180 define an organic light-emitting element.
The bank layer 190 defines an emission area of each of the pixel areas. The emission area may be a red emission area EA_R, a blue emission area EA_B, a green emission area EA_G depending on the type of a color filter layer in the pixel area. One or more signal lines are extended between two adjacent pixels. The signal lines may be a data line DL, a reference line Ref, or a supply voltage line VDD.
For example, white light emitted from the organic emission layer 175 in the red emission area EA_R passes through a red color filter layer CF-R to become red light, thereby producing red color. In doing so, the white light emitted from the organic emission layer 175 may not pass through the color filter layer CF disposed below the organic emission layer 175, such that the color purity and color gamut may be lowered.
For example, referring to FIG. 1, if all the white light emitted from the organic emission layer 175 in the red emission area EA_R passes through the red color filter layer CF-R as indicated by arrow {circle around (1)}, image quality with high red color purity can be achieved.
On the other hand, if a part of the white light emitted from the organic emission layer 175 in the red emission area EA_R passes through a color filter layer disposed in an adjacent pixel area (or an emission area) as indicated by arrow {circle around (2)}, blue light or green light may be produced even though the red pixel area is driven. As a result, the color purity and color gamut may be lowered, such that the quality of displayed image may be degraded.
In addition, for a bottom-emission OLED device, white light may be emitted from an organic emission layer toward top of the device such that the white light is reflected off a second electrode disposed above the organic emission layer to be scattered in random directions. Some of the scattered white light may pass through a color filter layer disposed in a pixel area or an emission area adjacent to a red pixel area such that blue or green color may be produced instead of red color, as indicated by arrow {circle around (3)}. As a result, the color purity and color gamut may be lowered. In particular, a transparent bank layer may transmit incident light, and thus an OLED device employing a transparent bank layer is vulnerable to the above-described problem.
In addition, the same problem may take place in the four-color OLED device shown in FIG. 2 as well.
When all the white light emitted from an organic emission layer 175 disposed in a white emission area EA_W with no color filter layer passes through a planarization layer 165 to propagate toward the bottom of the device as indicated by arrow {circle around (1)}, white light can be produced.
On the other hand, if a part of the white light emitted from the organic emission layer 175 in the white emission area EA_W passes through a color filter layer disposed in an adjacent pixel area or an emission area as indicated by arrows {circle around (2)} and {circle around (3)}, red light or blue light may be produced even though the white pixel area is driven. Moreover, a part of the scattered white light may skip a pixel area to pass through a green color filter layer, as indicated by arrow {circle around (4)}.
If a color filter layer is mislocated during a process of depositing a color filter layer due to processing deviation, the above-described problem may become even worse depending on the location and angle of the incident light on the color filter layer.